Possible Clues:

• Nervous reaction from tense bad speller?
• Pang; small noose
• Quiver spasmodically as in tic
• Nervous action
• Will she spell it out after tea, jerkily?
• Jerk about, hard?
• One may be nervous beginning to tackle weird sister
• Go looking for rare birds - spasmodic movement
• Move uncontrollably - watch birds
• A spasm of tic